<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
  <button>Act-once button</button>
  <script>
    let button = document.querySelector("button");
    function once() {
      console.log("Done.");
      button.removeEventListener("click", once);
    }
    button.addEventListener("click", once);
  </script>
</body>
</html>